1. Field of the Invention
The present invention relates to a communications system and a communications lighting apparatus, each using illumination light to accomplish optical communication.
2. Description of the Related Art
Recent years have seen a fast progress in broadband, wired or wireless communications technology as the increase in amount of personal use information. To be more specific, communication service using existing telephone lines, such as ADSL (Asymmetric Digital Subscriber Line), has come into use. Communication can therefore be achieved at high speed and low cost. The next-generation, high-speed communication means is optical communication. Light sources, communications modules, communications apparatuses and communications systems, all required in optical the home network or FTTH (Fiber-To-The-Home) network, either utilizing light, are now being developed.
The light-emitting means most widely used in our daily life is lighting apparatuses. The lighting apparatuses are indispensable to our life. They are installed everywhere and are used day and night. Lighting apparatuses generally used are fluorescent lamps and incandescent bulbs. They find their use in houses, working places, public institutions, and the like. To save energy, lighting apparatuses having light-emitting diodes (LEDs) or employing organic EL (Electric Luminescence) have been recently developed.
There are various systems in which light is used for communication. Among these systems is one used to control a robot. In this system, a light-emitting/receiving device is provided on the ceiling or wall of the room in which the robot works. Optical communication is performed between the robot and the light-emitting/receiving device. A system of this type is disclosed in, for example, Japanese Patent No. 2668793.
The system disclosed in Japanese Patent No. 2668793, however, is designed for limited use only, for example in plants. The information transmitted and received is limited to the data for controlling a robot. This system does not fully utilize lighting apparatuses that are light-emitting means widely and commonly used.
As pointed out above, lighting apparatuses are broadly used in our living space to apply light. The light they emit is not utilized in optical communication, however. This means that the existing lighting infrastructure is not fully used in our daily life.